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|Title: ||Liquid water on Enceladus from observations of ammonia and Ar-40 in the plume|
|Keywords: ||NEUTRAL MASS-SPECTROMETER;TITANS ATMOSPHERE;CASSINI ION;SOUTH-POLE;E-RING;ORIGIN;ABUNDANCES;VOLATILES;DEUTERIUM;RESERVOIR|
|Issue Date: ||2010-06-29 19:34:38 (UTC+8)|
|Abstract: ||Jets of water ice from surface fractures near the south pole(1) of Saturn's icy moon Enceladus produce a plume of gas and particles(2-5). The source of the jets may be a liquid water region under the ice shell-as suggested most recently by the discovery of salts in E-ring particles derived from the plume(6)-or warm ice that is heated, causing dissociation of clathrate hydrates(7). Here we report that ammonia is present in the plume, along with various organic compounds, deuterium and, very probably, Ar-40. The presence of ammonia provides strong evidence for the existence of at least some liquid water, given that temperatures in excess of 180 K have been measured near the fractures from which the jets emanate(8). We conclude, from the overall composition of the material, that the plume derives from both a liquid reservoir (or from ice that in recent geological time has been in contact with such a reservoir) as well as from degassing, volatile-charged ice.|
|Appears in Collections:||[天文研究所] 期刊論文|
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